*Smoking
        Hirdes, J. P., Forbes, W. F. 1989. Estimates of the relative risk of mortality based on the ontario longitudinal study of aging. Canadian Journal on Aging.  8 (3) 222-237.  
          Sorbye, L. W. 1988. [Nurses and smoking]. Sykepleien.  76 (2) 26-7.  
          Hirdes, J. P., Brown, K. S., Vigoda, D. S., Forbes, W. F., Crawford, L. 1987. Health effects of cigarette smoking: data from the Ontario Longitudinal Study on Aging. Canadian Journal of Public Health Revue Canadienne de Sante Publique.  78 (1) 13-7.